A scretch on a watch is hard.
When i bought watches, i get them without failures.
I like it, when my new watch is unworn.
Watches are detail instruments, things where milimeters and tiny details are important.
If a pre owner made scratches, because the person take not enough care, i will never want that watch.
Hopely you will receive a perfect Blancpain.
My Baume & Mercier Classima i have about 9 weeks, daily on my wrist and it shines as new.